That wide-open aperture… in full sun-light… I love it. F/2.8, and lower, gives us the feeling of intimacy and helps us achieve the “film” look. How much Neutral Density does it take to reach that look? More importantly, how much Neutral Density can one use before Infrared pollution changes the color of your blacks?
SUBTLE SHIFTS
The trouble with Infrared pollution is you might not notice a subtle shift in color when your shooting that important scene. Leaving you with difficult to color correct footage that might not match the rest of your film. That is why, as a cameramen, it is important to test your camera so you know where your Neutral Density breaks down and begins to introduce Infrared pollution. Personally, I hate guessing. I want to know exactly how to deliver consistent color and contrast throughout the scenes I am shooting.
TIFFEN IRND
Not all Infrared Filters are the same. A camera's sensor may need stronger or weaker Infrared filtration to help get the best out of the sensor. For reasons I do not totally understand, the Tiffen series of IR filtration works really well with the Blackmagic cameras: Cinema Camera, Pocket Camera, and the 4K Production Camera… Tiffen and Blackmagic… they just work. If you have a Red camera or a Sony F5 then you'll want to do your own test and settle on the best filters that match your camera's sensor.
THE TEST
My intention was to keep this test very simple. All that was needed were my filters and a strong and consistent light source. I shot this in my front yard in the hour before sunset. When you watch these tests take special attention to the black color chips on the color chart. You can see how much the Infrared pollution changes the hue and saturation.
IRND Step Test from Brian Hallett on Vimeo.
IRND Side-by-Side test from Brian Hallett on Vimeo.
THE RESULTS
If you looked at these tests and thought to yourself “Hey, I really like how the Infrared warms the image.” I have a warning for you… your blacks will be brown and there will be nothing you can do about it. I have learned this the hard way. In the video below, Shot on the Blackmagic Cinema Camera, I had a number of subjects who were wearing black sweaters, shirts, and an apron. All the black fabric came out a reddish brown. For example. at :08 she had on a black shirt, at :14 his shirt, in real life, was more black than reddish brown, and at :40 her sweater was definitely closer to black in person… now it looks a not so pleasant reddish brown. Now, this was a news-style shoot and I doubt the people we surprised saw this video and wondered why their clothing looked different on TV. On the other hand, had this been a bigger production with more on the line… I doubt this would have gone unnoticed.
Surprise Squad “Free Gas” from Brian Hallett on Vimeo.
CONCLUSION
The Infrared Filtration needs for the Blackmagic Production Camera are very similar to the infrared filtration needs of the Cinema Camera and Pocket Cinema Camera. All three need IRND in the 1.8, and 2.1 stop range. To me 1.2 and 1.5 are gray areas. 1.2 with straight ND causes a little bit of Infrared pollution, but it is very mild. Then again, 1.5 with IRND is a little over corrected and can have a little too much of a greenish hue. Personally, I will stay away from guessing and either shoot with a .09 ND or a 1.8 IRND. In the end, do your own test. Know your camera so you know when to make the call on set.
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